Intro to Your Immune System | Episode 1
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[00:00:00] ​Welcome back everyone to the first episode of season 3 of the Crunchy Allergists Podcast.
[00:00:09] If this is our first time meeting, Welcome!
[00:00:11] Hello, my name is Dr Kara Wada. I'm a practicing pediatric and adult allergy immunology and lifestyle medicine, physician. I'm a certified life coach, mom of three, a wife and a systemic Sjogrens patient.
[00:00:25] It's because of everything I learned and went through as a patient though, that I've made it my mission in life to use the privilege I have as a physician to help us all navigate our health and wellness more effectively and efficiently.
[00:00:39] To find ways to ensure we are fully seen and cared for as patients and as people.
[00:00:45] One of the main ways I love to do that is empower people with education. It is so helpful to know what exactly is going on when our body decides [00:01:00] to misbehave or not read the textbook as I will many times tell my patients.
[00:01:06] Over this last year and recording over 52 episodes of the podcast, one of the things that has come up repeatedly from my patients, especially, is asking that I record some of the conversations that I commonly have with them in the office.
[00:01:24] To educate them about what may be going on with their immune system, whether it be related to allergies or autoimmunity or immune deficiency in particular. How they many times have wanted to go back and learn again. Get more pearls out of what I've had to say.
[00:01:43] So this is my love letter to all of my patients and I am so excited that I'm going to be able to introduce you to many of my esteemed colleagues and share [00:02:00] conversations that we are having about different conditions that we care for in the office day in and day out.
[00:02:10] We will be learning from everything about food allergies and treatments that are up and coming for food allergies. We're going to be talking about runny noses and nasal polyps, asthma. We talked about chronic hives last year, but we'll talk a little bit more about hives and anaphylaxis.
[00:02:30] A colleague who is an expert in alpha gal syndrome, which if you haven't heard of it is a condition where people become allergic to mammalian meat through a tick bite which is so bizarre that if it weren't true, it would be hard to believe.
[00:02:49] Functions of our Immune System
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[00:02:49] But in this first episode, I want to set the stage by introducing you to your immune system.
[00:02:59] What [00:03:00] are the names and pieces of the puzzle? How do they work and what different things go wrong when the immune system is not functioning optimally?
[00:03:18] Let's just start off initially by talking about the functions of our immune system. First and foremost, our immune system is there to prevent or eradicate infections. These infections could be due to a virus, bacteria, parasite.
[00:03:42] Our immune system though, also helps defend us against tumors and cancers. It controls tissue regeneration and scarring.
[00:03:57] The immune system also can [00:04:00] injure cells itself and induce inflammation that's actually harmful. This is what happens in allergy or auto-immunity and in some other inflammatory conditions.
[00:04:13] The immune system also recognizes and responds to things that it deems as not being our own. This comes up in the case of those who have undergone a transplant, like an organ transplant. The body without sufficient treatment may recognize that kidney or that liver or those lungs as someone else's because they actually are.
[00:04:41] That's why those people need to take immune suppressing or immune decreasing medications in order to prevent their immune system from attacking and damaging that organ that's new to them.[00:05:00]
[00:05:00] Two Types of Immunity
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[00:05:00] What we're going to cover in this episode are what types of immune responses protect us from infections. What are the important characteristics of immunity and what mechanisms are responsible for those different characteristics? How are the cells and tissues of the immune system organized so that they can find and respond to microbes or infections in ways that lead to their eradication?
[00:05:29] First we need to think about how we categorize the different parts of our immune system. When we think about our immune system, it gets complicated really quickly. So having a framework that we can use to understand how all of these different cells and tissues work together in order to help our body stay [00:06:00] healthy is really important.
[00:06:04] We have two big categories that we consider when we're talking about immunity. The first is innate immunity and the second is adaptive immunity.
[00:06:19] Innate immunity provides immediate protection. So innate immediate. Adaptive immunity develops more slowly and provides a more specialized defense against infections.
[00:06:36] Innate Immunity
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[00:06:36] We're going to start with* innate immunity*.
[00:06:39] Innate immunity is also called our natural immunity. This is always present in healthy people. Now there there's always a little asterix. There are some folks who are born with missing pieces of their innate immune system, we'll tackle that at some other time. [00:07:00] But in a healthy individual, these are things that we are born with and we will continue to have over the course of our lifespan.
[00:07:09] These are strategies that our body has developed to prevent different microbes from entering ourselves or body. Our present to help rapidly eliminate them so that they can't enter our tissues.
[00:07:26] Innate immunity is really old. We share things in our innate immune system that are also present in starfish. If you're remembering way back to biology and when starfish and future humans would have divided, it was a long, long time ago. Some of these capabilities are immensely old.
[00:07:50] When we think about our innate immune system, things that fall under that category our skin. Our epithelial barriers keeps [00:08:00] our outside away from our insides. That's part of our immune system. The cells that we find close to our epithelial or skin barrier.
[00:08:09] Next we have all of the white blood cells that are considered innate immune white blood cells, mass cells. Which we're going to talk a lot about in the next few weeks.
[00:08:22] Phagocytes. Those are cells that eat microbes for breakfast. They actually then become pus once they fulfill their duties.
[00:08:34] Dendritic cells. These are cells that are found throughout our skin. They have long arms and little fingers. They look they're called dendritic cells because they look a lot like dendrites, which are cells in our brain. They have these long arms and they're sampling things all the time. They're taking little bits and pieces and seeing what self, what's not self, what's [00:09:00] infection. They're helping then coordinate the response between our innate means system and then to our adaptive immune system, which we'll get to in a minute.
[00:09:11] The innate immune white blood cells also include natural killer cells, which are a little bit like assassins and a specialized type of other innate lymphoid cells, which we'll just leave N-O-S, not otherwise specified. There are all sorts of types of them, but we want to keep this as immunology 101 and not get too stuck in the weeds.
[00:09:41] Our innate immune system also includes the compliment system. Compliment is a quite complicated system that is a series of proteins that work together to primarily make [00:10:00] microbes appear more yummy to our other white blood cells.
[00:10:04] Adaptive Immunity
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[00:10:04] Moving on to our adaptive immune system. Our adaptive immune system primarily is composed of our lymphocytes. These are white blood cells that have an ability to make memory to things that we have seen and encountered.
[00:10:21] This includes our B lymphocytes, which can also then become plasma cells. Plasma cells are specialized B lymphocytes that then produce antibodies. Antibodies are proteins that provide an opportunity for our body to keep memory to things that we have encountered.
[00:10:41] We also have T lymphocytes and these then will become what we call effector T cells. So there's both memory and killer T cells. That then help provide defense against particular types of infections. [00:11:00]
[00:11:00] The adaptive amine system is really important because it allows our body to learn as we go through life, when we encounter things in our environment, infections, or even foods as we are learning to eat.
[00:11:27] Those molecules had the potential to be specifically recognized by lymphocytes or antibodies, and those are then called antigens.
[00:11:39] Adaptive immune responses will often use cells and molecules in the innate immune system together with the adaptive immune system. So even though we call these two separate kind of wings of the immune system, they're always working together.
[00:11:58] We just use these two [00:12:00] categories to help us better understand what their capabilities are and to help provide some context. Like I said, a framework because things get complicated quite quickly.
[00:12:11] Properties of Adaptive Immune Response
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[00:12:11] As we think about our adaptive immune responses. What's really cool about these responses, they're specific. This ensures that the immune response is precisely targeted to that pathogen or that microbe.
[00:12:31] It's also diverse. It enables our immune system to respond to a large variety of antigens, all different types of viruses, bacteria, parasites, you name it.
[00:12:41] As memory, as I've mentioned, which allows us to have a long term memory or response so that if we see the same type of infection over and over again that we learn from that. It's not like we're back at square one. [00:13:00]
[00:13:00] There's also this idea of clonal expansion. This increases the number of antigen specific lymphocytes, those B and T cells from a small number of naive or like baby B cells and T cells.
[00:13:15] Essentially, the immune system will create clones of itself in order to eradicate an infection. In the midst of fighting off that infection. So if you've caught a cold and you're feeling pretty cruddy, you maybe have a fever, you feel run down. But within a day or so you're back to feeling pretty okay.
[00:13:40] Part of that is your memory but also it's something called clonal expansion. Your body is recognizing that it's seeing the rhino virus again for the bazillionth time. It is then creating a specific force defense force [00:14:00] to take out that particular infection and it's going to expand colonially the cells that it specifically needs to do that.
[00:14:12] This is also where specialization comes into play. We have particular cells that do a better job of eradicating viral infections or particular types of bacterial infections. So on and so forth.
[00:14:29] When we think about the workforce that's needed to eradicate an infection, we're talking about millions of cells. After an infection is done, the body needs to be able to clean up the mess that's left and also turn off that huge concerted effort of inflammation so that the body isn't continuing to expend that [00:15:00] energy that it's been needing to fight that infection.
[00:15:03] This is then the ability for our adaptive immune system to contract or to shrink back down to normal and to go back to, we call homeostasis, trying to come back to this balance point.
[00:15:18] Ideally, our adaptive immune system also is non-reactive to self. This is what prevents injury to our own cells even when we're fighting off an infection. As we know though, if you are someone who suffers from autoimmunity. This doesn't always go exactly according to plan.
[00:15:43] Other Features of Adaptive Immunity
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[00:15:43] Let's talk a little bit more about some of the other parts of our immune system. We've talked a little bit about some of the specific pieces. Some of the proteins and cells in particular, but all of these different pieces need [00:16:00] someplace to call home.
[00:16:02] There are particular tissues and organs that are considered immune system components as well. This includes our bone marrow, which is where many of our blood cells, both white blood cells and red blood cells are created. We also have our thymus, which is where our T cells go to school and our lymph nodes, which I like to call our speed dating coffee shop club. Place where our that's where our T-cells and B-cells in particular, going to communicate with one another and if they find a match that is where many times that clonal expansion will occur.
[00:16:54] That's why when you're sick, it's not uncommon that you will feel a lymph node in [00:17:00] particular in your neck, if you're dealing with a cold, that is tender and swollen.
[00:17:07] Our spleen is also another significant organ in our immune system function. Our spleen is essentially a floppy bag of tissue that lays on our left side, in the backside of our ribs.
[00:17:28] It is another place where white blood cells will come to congregate. Do a little speed dating. But also this is a place where our damaged blood cells will also be filtered from the circulation.
[00:17:49] Tissues of the Immune System
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[00:17:49] Other tissues that don't get as much discussion or attention, but are extremely important. Our mucosal and our [00:18:00] cutaneous lymphoid tissues.
[00:18:01] Let me define what those words are, that's a lot of complicated words. Mucosal surfaces are any surfaces that are typically more moist in our body, inside of our nose, back of our throat, our mouth. Our whole GI track, so our stomach, our intestines, our colon. Our genital urinary track, vaginal tissues. Even around our eyes as well.
[00:18:35] Cutaneous means skin so that's the epithelial barrier we were talking about as well. There are other congregations or collections of white blood cell containing tissues throughout those tissues and in part it's because these are the interfaces where our [00:19:00] outsides and our insides meet.
[00:19:03] We think about the air we breathe. Air comes in through our nose or mouth. Ideally, it comes in through our nose. It's filtered. Particulate is filtered out through our little nose hairs and our mucus that's there. That's also part of our immune system.
[00:19:21] The air is warmed up and humidified, as it passes through our nasal passageways or sinuses. Down through the back of our pharynx or throat and then through our vocal chords, if we're talking. Down our bronchial tree and then into our lungs.
[00:19:42] All of those tissues have immune system cells that are present. That are serving as watch men looking for potential viral particles or other [00:20:00] substances that our body might deem as a dangerous signal.
[00:20:06] For some of us, this may be the center of a strong fragrance, or a really high pollen day, or someone's smoking. All of these things can trigger inflammation in our respiratory track because our body is trying to protect us from something it deems as a potential danger.
[00:20:37] So I think that is plenty to cover for our first episode. Stay tuned!
[00:20:43] Next week, I am going to dig little bit deeper into the innate immune system.
[00:20:48] That part of our immune system that has been there since the beginning and we'll talk more about specific cells, how they work [00:21:00] together, and how when things go wrong that we can see those effects in inflammation in our body.
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